The present invention relates to a cooling system for cooling a space in a room and, more particularly to a cooling system for cooling telecommunication equipment at a radio relay station located in desert or like regions where there is a large difference between the daytime and nightime temperatures.
Still more particularly, the invention is concerned with a non-powered cooling system having refrigerant circulated naturally by gravity without making use of any external power. Low temperature energy or cooling energy is stored in a heat accumulator or storage at night when outdoor temperature is low, for release from the heat storage to effectively cool the telecommunication equipment during daytime when the temperature is high.
There have been a remarkable growth of microwave communication systems for covering wide areas in various regions of the world. In a long-distance microwave communication system, it is necessary to construct unattended relay stations at intervals of 10 to 50 Km.
FIGS. 1A and 1B schematically show the construction of a typical conventional radio relay station, which has a steel tower 20 for supporting a parabolic antenna, and a shelter for accommodating various telecommunication equipment 2'. In this conventional relay station, the maximum power consumed by these quipment is as large as about 1 Kw. To cope with this demand for electric power, in the conventional relay station, it has been necessary to generate a large electric power by means of a generator 22 driven by a diesel engine or the like. Generated electric power is supplied, through a rectifier 23 and batteries 24, to the telecommunication equipment 2', and also to a motor-driven compressor of a cooling system 4', for cooling the telecommunication equipment 2'. Thus, the conventional relay station required a frequent supply of fuel and maintenance work.
However, as a result of recent development of semi-conductor devices, the power consumption on the part of the telecommunication equipment has been reduced to 50 to 150 W (43 to 129 Kcal/hr) which is only 1/20 to 1/6 of that consumed by the conventional one. Consequently, a power supply means of much smaller capacity suited for unattended relay stations, such as battery or solar battery, has become sufficient for the telecommunication equipment. Under the circumstances, the power consumption on the part of the motor-driven compressor of the cooling system, which amounts to 0.75 Kw or so, is impractically large.
For this reason, there is an increasing demand for the non-powered cooling system which requires no maintenance work.